Applications employing optical systems integrated into optoelectronic modules can be highly sensitive to tolerances in the optical systems. Such tolerances include optical element sub-assembly tolerances (e.g., off-center, tilted, decentered optical elements (i.e., centration error with respect to two or more optical elements)), tolerances in optical element surface profiles (e.g., decentered surfaces within a single optical element (prevalent in lower quality (e.g., injection molded) optical elements)), optical system to image sensor sub-assembly tolerances, and/or optical system to light-source sub-assembly tolerances. These tolerances can result in distortion asymmetry, for example.
In some instances when optical systems are employed to focus an image onto an image plane (coincident with an image sensor), the image collected by the image sensor can exhibit significant distortion asymmetry. Accordingly, the image quality of the collected image can be rather poor. In other instances, for example, when optical systems are employed to project or cast a pattern or image onto a plane in the far field, the image or pattern can exhibit significant distortion asymmetry. In such instances, the projected or cast pattern or image may be used for structured light applications (i.e., to collect three-dimensional data), but the distortion asymmetry can be highly problematic (e.g., precision and/or accuracy of the three-dimensional data may be dramatically compromised).
Active alignment can be used to correct for the aforementioned tolerances. Active alignment, however, can be time-consuming and thus not conducive to large-scale production of optical systems/optoelectronic modules. For example, active alignment of an optical system relative to an image sensor might involve recording data (e.g., images) via the image sensor and actively tilting the optical system with respect to the image sensor until substantially distortion-free data (e.g., an image) is obtained. Uncured epoxy interposed between the optical system and the image sensor would then be cured to fix the optical system in place.